Sparse Learning over Infinite Subgraph Features
This addresses the challenge of feature selection from an infinite set of subgraph candidates for researchers in graph machine learning, though it appears incremental as it generalizes prior techniques.
The paper tackles the problem of supervised learning from graph data by developing an algorithm for sparse linear models over infinite subgraph features, resulting in a fast-converging method that solves a wider class of problems compared to existing approaches.
We present a supervised-learning algorithm from graph data (a set of graphs) for arbitrary twice-differentiable loss functions and sparse linear models over all possible subgraph features. To date, it has been shown that under all possible subgraph features, several types of sparse learning, such as Adaboost, LPBoost, LARS/LASSO, and sparse PLS regression, can be performed. Particularly emphasis is placed on simultaneous learning of relevant features from an infinite set of candidates. We first generalize techniques used in all these preceding studies to derive an unifying bounding technique for arbitrary separable functions. We then carefully use this bounding to make block coordinate gradient descent feasible over infinite subgraph features, resulting in a fast converging algorithm that can solve a wider class of sparse learning problems over graph data. We also empirically study the differences from the existing approaches in convergence property, selected subgraph features, and search-space sizes. We further discuss several unnoticed issues in sparse learning over all possible subgraph features.